The noncrossing matchings with each of their blocks containing a given element are introduced and studied. The enumeration of these matchings is described through a polynomial of several variables, which is proved to satisfy a recursive formula. Results of the enumeration of noncrossing matchings with fixed points are connected with Catalan numbers.
Citation
Weiming Weng, Bolian Liu. Noncrossing Matchings with Fixed Points[J], Ars Combinatoria, Volume 109. 161-170. .